This invention relates to a method and apparatus involving an electrochemical cell. The electrochemical cell has a bed type electrode of conductive particles that are dynamically packed together by a rapidly flowing electrolyte.
Discrete conductive particles have been used for porous electrochemical cell electrodes in several forms. In one type the conductive particles are bonded together, with or without compression, to form a porous body or briquette. In another type, the conductive particles are packed in a fixed relationship between two retaining screens, forming a fixed bed electrode. It is also known to suspend the conductive particles in a flowing electrolyte to form a moving slurry or a fluidized bed of conductive particles.
All of these approaches to making electrodes of conductive particles while possessing certain advantages, also have certain disadvantages. For example, bodies of bonded particles form low electrical resistance electrodes. However, such electrodes generally present a high resistance to flow of electrolyte through them, resulting in low mass transfer rates. Fixed bed electrodes have higher mass transfer rates. On the other hand, they are subject to channeling. Fluidized bed and slurry electrodes have high mass transfer rates but have poor electrical conductivity.
We have now found a superior type of particle electrode, as well as a method and system for using it. Our method and system provide slow electrical resistance and high mass transfer rates, without problems of channeling.